A reflected cross-site scripting vulnerability in the login page of Zimbra Collaboration Suite (ZCS) allows an unauthenticated attacker to execute JavaScript through the zrememberme parameter. A crafted relogin URL selects a two-factor error display that inserts the parameter into a hidden input attribute without HTML encoding. A victim who opens the URL receives attacker-controlled script and page content under the legitimate Zimbra origin, allowing credential capture through a replacement login form. The relogin path logs out an existing session before rendering the payload, so the demonstrated attack does not inherit that session's mailbox access. ZCS 10.1.16 and 10.1.17 are affected.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 9
- Cpes+1 CPE criteria (now 1)NVD modified 2026-10-28 21:13
- StatusPublished → AnalyzedNVD modified 2026-10-28 21:13
- StatusUndergoing Analysis → PublishedNVD modified 2026-10-28 19:49
- StatusPublished → Undergoing AnalysisNVD modified 2026-10-28 20:18
- StatusAwaiting Analysis → PublishedNVD modified 2026-10-23 13:28
- StatusPublished → Awaiting AnalysisNVD modified 2026-10-23 16:44
- StatusReceived → PublishedNVD modified 2026-10-23 13:28
- StatusPublished → ReceivedNVD modified 2026-10-23 14:17
- First seenCVSS 6.1 · zimbraNVD modified 2026-10-23 13:28
Affected (CPE criteria) 1
cpe:2.3:a:synacor:zimbra_collaboration_suite:*:*:*:*:*:*:*:*
References 2
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories Vendor Advisory
- https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/ Exploit, Third Party Advisory